Try to fill the board with the same colour. Imagine you are using the fill tool of the scratch editor. Every turn you will give a number which corresponds with the circles at the top. The game will then take that number's colour and use it will a fill tool on the TOP LEFT pixel. (every pixel of the same colour touching this pixel will turn to that colour.) The game will sense that the board is complete and end the game.
The original Drench flash game: http://www.flashbynight.com/drench/ Music is Bit Stream by Kevin MacLeod: https://www.youtube.com/watch?v=9np9KK4ccuA